1. Field of the Invention
The present invention relates generally to dust collecting apparatus. More particularly, the invention concerns an attachment for hand-held power tools for collecting debris generated during the use of the power tool in cutting plaster and various other materials.
2. Discussion of the Invention
Hand-held power tools, such as grinders and saws are widely used in the building industry. Such tools typically embody rotating cutting members, such as circular grinding wheels and blades that are typically rotated at several thousand revolutions per minute. These tools are used to cut plaster, ducting, tile and various other materials. During the cutting operation, particles resulting from the cut are expelled at high velocity into the surrounding environment presenting a substantial hazard to the operator and causing the contamination of tools and other articles that may be located proximate the work site.
When the tools are used to cut ducting which is covered with asbestos materials, a serious health hazard is created if the particulate matter emanating from the cutting operation is not immediately captured and contained.
Most commercially available hand-held power tools, such as grinders are provided with guards that cover a portion of the rotating cutting element and protect the operator from contacting the cutting element during cutting operations. However, these guards are totally ineffective in controlling dust contamination. Accordingly, attempts have been made in the past to attach vacuum hoses to the protective guard to collect dust produced during cutting operations. One such arrangement is described in U.S. Pat. No. 3,882,598 issued to Earle, et al. A somewhat similar arrangement is also disclosed in U.S. Pat. No. 4,022,182 issued to Lenkwich.
In U.S. Pat. No. 4,253,362 issued to Olson, a dust collecting apparatus for circular power saws is disclosed. This apparatus includes an integral sleeve which is attached to the guard casing of the saw and a tube which is slidably received in the sleeve so that one end of the tube can be adjustably positioned proximate the rearward extremity of the saw blade. The other end of the tube is connected with a vacuum source so that dust produced by the cutting blade can be captured. Clamping means are provided for holding the tube in a fixed position relative to the rearward periphery of the saw blade.
A pneumatic cutter for cutting concrete, which includes a suction pipe coupled to a disc cutter covering the cutter member, is disclosed in U.S. Pat. No. 4,974,907 issued to Komura. A somewhat similar device is illustrated and described in U.S. Pat. No. 3,585,980 issued to Mellor. The device of this latter patent is especially designed to remove mortar from between rows of bricks. Still another type of dust confining and collection housing is described in U.S. Pat. No. 4,255,995 issued to Connor.
Most of the prior art dust collection devices are designed for use with power tools, such as circular saws, that are most often,used for cutting horizontally disposed planar work pieces such a sheets of plywood and the like. When the power tool is used for such cutting operations, the dust collection devices work in an acceptable manner and do not interfere with the cutting operation. However, when the hand-held power tool is to be used for cutting overhead workpieces or for cutting ducting and the like many of the prior art duct collection devices fail to work properly and often interfere with the cutting operation.
The thrust of the present invention is to provide a novel dust collecting apparatus that can be used with a variety of different types of hand-held power tools such as grinders, and one that is uniquely designed to insure that the cutting debris is effectively captured even when the power tool is used for overhead cutting or for cutting of irregular workpieces at odd angles. More particular, the novel apparatus of the invention includes a guard that replaces the guard provided with the tool, a sleeve attached to the guard and a tube which is telescopically movable within the sleeve from an extended position to a retracted position. The tube includes a first end having a workpiece engaging foot which is maintained in constant engagement with the work during the cutting operation by a biasing means which is carried within the sleeve. A vacuum source is interconnected with the sleeve so that debris generated during the cutting operation is efficiently captured and safely carried way from the cutting site. This arrangement is invaluable when the power tool is used, as for example, in cutting plaster or gypsum board overhead ceilings. In such cases, the work engaging foot of the apparatus is maintained in firm and steady engagement with the ceiling during the cutting operation and the dust collection apparatus in no way interferes with the use of the power tool.